2025, 39(1): 1-5.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0700
Abstract:
To objectively evaluate the feasibility of dewatering recharge in deep foundation pit in pebble stratum, the key factors affecting the feasibility of recharge were analyzed, the classification of the feasibility of recharge and the corresponding evaluation index levels were determined. Based on Euclid approach degree and grey correlation degree analysis, a multi-factor and multi-level comprehensive evaluation model for recharging feasibility was proposed. By analyzing the correlation degree between the parameters of deep foundation pit engineering and the evaluation index of recharge feasibility, the feasibility grade of dewatering recharge of deep foundation pit engineering can be determined. The reliability of the recharge feasibility analysis was verified by a case study of the recharge project, and the results show that the method of the recharge feasibility analysis based on Euclid approach degree and grey correlation degree can provide references for recharge design.
To objectively evaluate the feasibility of dewatering recharge in deep foundation pit in pebble stratum, the key factors affecting the feasibility of recharge were analyzed, the classification of the feasibility of recharge and the corresponding evaluation index levels were determined. Based on Euclid approach degree and grey correlation degree analysis, a multi-factor and multi-level comprehensive evaluation model for recharging feasibility was proposed. By analyzing the correlation degree between the parameters of deep foundation pit engineering and the evaluation index of recharge feasibility, the feasibility grade of dewatering recharge of deep foundation pit engineering can be determined. The reliability of the recharge feasibility analysis was verified by a case study of the recharge project, and the results show that the method of the recharge feasibility analysis based on Euclid approach degree and grey correlation degree can provide references for recharge design.
2025, 39(1): 6-13.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0646
Abstract:
According to Mindlin’s displacement solution regarding a semi-infinite mass subjected to a point load, the calculation formulas for vertical displacement caused by skin friction in piles under uniformly distributed loads have been derived thoroughly. This includes scenarios with linearly increasing distribution loads along the length of the pile and arbitrary distribution loads within uniform foundations. Through concrete project examples, it is confirmed that these formulas are both accurate and practical. The formula presented plays a crucial role in calculating the settlement of pure friction single piles, the elastic deformation in the early stage of pile and soil under load, and the comparison of elastic-plastic deformation and finite element calculation. The strata in some areas of Xi’an are mainly composed of medium and low compressible loess and paleosol, and the soil quality is relatively uniform. The results obtained by this calculation method are reliable and have practical application value.
According to Mindlin’s displacement solution regarding a semi-infinite mass subjected to a point load, the calculation formulas for vertical displacement caused by skin friction in piles under uniformly distributed loads have been derived thoroughly. This includes scenarios with linearly increasing distribution loads along the length of the pile and arbitrary distribution loads within uniform foundations. Through concrete project examples, it is confirmed that these formulas are both accurate and practical. The formula presented plays a crucial role in calculating the settlement of pure friction single piles, the elastic deformation in the early stage of pile and soil under load, and the comparison of elastic-plastic deformation and finite element calculation. The strata in some areas of Xi’an are mainly composed of medium and low compressible loess and paleosol, and the soil quality is relatively uniform. The results obtained by this calculation method are reliable and have practical application value.
2025, 39(1): 14-24.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0783
Abstract:
Based on the idea of discretization, the spring element method was introduced into the mechanical analysis of the anchorage system, and the relationship between the displacement distribution function, the axial force distribution function and the lateral resistance distribution function was established. Considering the softening characteristics of the anchorage interface, the softening process of the anchorage interface was simulated by assuming that the ultimate lateral resistance decays to the residual frictional resistance in the form of linear and exponential curves, respectively. The influence of interface softening characteristics on the pull-out mechanical behavior of the anchorage system was analyzed, and finally verified through on-site pull-out tests. Research has shown that considering the softening characteristics of the anchorage interface can more accurately reflect the stress deformation characteristics of the anchorage system. Whether it is linear softening or exponential curve softening, the difference in analysis results between the two is very small when appropriate softening coefficients are selected.
Based on the idea of discretization, the spring element method was introduced into the mechanical analysis of the anchorage system, and the relationship between the displacement distribution function, the axial force distribution function and the lateral resistance distribution function was established. Considering the softening characteristics of the anchorage interface, the softening process of the anchorage interface was simulated by assuming that the ultimate lateral resistance decays to the residual frictional resistance in the form of linear and exponential curves, respectively. The influence of interface softening characteristics on the pull-out mechanical behavior of the anchorage system was analyzed, and finally verified through on-site pull-out tests. Research has shown that considering the softening characteristics of the anchorage interface can more accurately reflect the stress deformation characteristics of the anchorage system. Whether it is linear softening or exponential curve softening, the difference in analysis results between the two is very small when appropriate softening coefficients are selected.
2025, 39(1): 25-34.
doi: 10.20265/j.cnki.issn.1007-2993.2024-0252
Abstract:
The influence caused by the reinforcement range of the connecting passage on the main tunnel during the construction process of the connecting passage of subway shield tunnels was investigated. Through numerical simulation, the influence of the reinforcement range of the stratum on the mechanical behavior of the main tunnel segment, such as the overall deformation of the main tunnel segment, the stress and displacement of the special segment, and the stress state of the bolts between the special and ordinary segments, was comprehensively analyzed. The results show that: (1) Ground reinforcement can significantly reduce the maximum tensile stress of special segments, but it will significantly increase the maximum compressive stress, and the control effect on lateral expansion displacement and vertical convergence displacement was limited. (2) Proper reinforcement can significantly reduce the maximum tensile stress of the bolt, greatly reduce the top settlement displacement of the transverse channel, and slightly reduce the bottom uplift displacement, which is conducive to the overall deformation control of the transverse channel. However, when the reinforcement range is too large, the maximum tensile stress of the bolt rises significantly. Considering the factors such as the economy and construction effect, full-length reinforcement should be avoided.
The influence caused by the reinforcement range of the connecting passage on the main tunnel during the construction process of the connecting passage of subway shield tunnels was investigated. Through numerical simulation, the influence of the reinforcement range of the stratum on the mechanical behavior of the main tunnel segment, such as the overall deformation of the main tunnel segment, the stress and displacement of the special segment, and the stress state of the bolts between the special and ordinary segments, was comprehensively analyzed. The results show that: (1) Ground reinforcement can significantly reduce the maximum tensile stress of special segments, but it will significantly increase the maximum compressive stress, and the control effect on lateral expansion displacement and vertical convergence displacement was limited. (2) Proper reinforcement can significantly reduce the maximum tensile stress of the bolt, greatly reduce the top settlement displacement of the transverse channel, and slightly reduce the bottom uplift displacement, which is conducive to the overall deformation control of the transverse channel. However, when the reinforcement range is too large, the maximum tensile stress of the bolt rises significantly. Considering the factors such as the economy and construction effect, full-length reinforcement should be avoided.
2025, 39(1): 35-41.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0639
Abstract:
A foundation pit excavation was located in Beijing urban area with a depth of approximately 16.5 meters, with a local deepened area of up to 20.4 meters. Surrounding the excavation were numerous utility lines and residential buildings, as well as multiple layers of groundwater within the excavation depth range. The groundwater control design utilized a thick overlapping bottom-fall curtain wall to effectively solve the problem of groundwater seepage, suppressed the additional settlement of surrounding soil layers, and played a positive role in controlling the deformation of surrounding buildings. According to the local condition, emergency depressurization wells were set up around the excavation and in the local deepened area, effectively ensuring the construction of water-submerged anchor rods and playing a positive role in preventing the sudden surge of confined water. The foundation pit support design adhered to the principle of displacement control, combining numerical and theoretical calculations to predict the deformation of deep foundation pit. A standard for the displacement control of support structures was proposed, and different stiffness support systems were selected based on the degree of sensitivity of the surrounding environment. Specific requirements were also made for the construction process of anchor rods and water control measures to effectively ensure the safety and normal use of the foundation pit and surrounding environment while saving time and costs.
A foundation pit excavation was located in Beijing urban area with a depth of approximately 16.5 meters, with a local deepened area of up to 20.4 meters. Surrounding the excavation were numerous utility lines and residential buildings, as well as multiple layers of groundwater within the excavation depth range. The groundwater control design utilized a thick overlapping bottom-fall curtain wall to effectively solve the problem of groundwater seepage, suppressed the additional settlement of surrounding soil layers, and played a positive role in controlling the deformation of surrounding buildings. According to the local condition, emergency depressurization wells were set up around the excavation and in the local deepened area, effectively ensuring the construction of water-submerged anchor rods and playing a positive role in preventing the sudden surge of confined water. The foundation pit support design adhered to the principle of displacement control, combining numerical and theoretical calculations to predict the deformation of deep foundation pit. A standard for the displacement control of support structures was proposed, and different stiffness support systems were selected based on the degree of sensitivity of the surrounding environment. Specific requirements were also made for the construction process of anchor rods and water control measures to effectively ensure the safety and normal use of the foundation pit and surrounding environment while saving time and costs.
2025, 39(1): 42-48.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0699
Abstract:
Based on the foundation pit and pipe jacking project of an underground passage near a tunnel in Ningbo, combined with incorporating monitoring data, an analysis was conducted on the impact of the whole construction process on the adjacent subway tunnel. Monitoring data indicate that full-circle MJS, cement mixing piles, and high-pressure jet grouting piles significantly influenced the tunnel, causing substantial uplift, horizontal displacement away from the construction area, and diameter reduction. Additionally, untimely pouring of the base slab, consecutive removal of two supports, and prolonged incomplete closure of the top slab resulted in significant increases in tunnel horizontal displacement and convergence. During the pipe jacking, deformations in parallel and underpass tunnels included initial settlement, increased uplift, and later subsidence. For complex underground projects near subways, emphasis on comprehensive deformation control is essential to achieve tunnel deformation management.
Based on the foundation pit and pipe jacking project of an underground passage near a tunnel in Ningbo, combined with incorporating monitoring data, an analysis was conducted on the impact of the whole construction process on the adjacent subway tunnel. Monitoring data indicate that full-circle MJS, cement mixing piles, and high-pressure jet grouting piles significantly influenced the tunnel, causing substantial uplift, horizontal displacement away from the construction area, and diameter reduction. Additionally, untimely pouring of the base slab, consecutive removal of two supports, and prolonged incomplete closure of the top slab resulted in significant increases in tunnel horizontal displacement and convergence. During the pipe jacking, deformations in parallel and underpass tunnels included initial settlement, increased uplift, and later subsidence. For complex underground projects near subways, emphasis on comprehensive deformation control is essential to achieve tunnel deformation management.
2025, 39(1): 49-54.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0702
Abstract:
Micro-steel pipe piles are widely used in landslide control project for their low cost, short construction period, and flexible layout. Due to the fact that most micro steel pipe piles are arranged in large groups, grouting construction will have an impact on the natural discharge of groundwater, leading to an increase in the groundwater level on the slope and thus affecting the effect of landslide control. Therefore, when using micro steel pipe piles for landslide control, the issue of groundwater discharge at the back of the pile group should be considered. Taking the emergency control project of a natural gas pipeline landslide in Guizhou as an example. By optimizing the layout and construction technology of steel pipe piles, a reasonable groundwater drainage channel was reserved between pile groups, effectively reducing the groundwater level at the back of the pile group and reducing the landslide thrust behind the piles. After the completion of steel pipe pile construction, the overall stability of the landslide indicates that the treatment plan is reasonable and feasible, which can provide reference for the design and construction of similar landslide prevention projects.
Micro-steel pipe piles are widely used in landslide control project for their low cost, short construction period, and flexible layout. Due to the fact that most micro steel pipe piles are arranged in large groups, grouting construction will have an impact on the natural discharge of groundwater, leading to an increase in the groundwater level on the slope and thus affecting the effect of landslide control. Therefore, when using micro steel pipe piles for landslide control, the issue of groundwater discharge at the back of the pile group should be considered. Taking the emergency control project of a natural gas pipeline landslide in Guizhou as an example. By optimizing the layout and construction technology of steel pipe piles, a reasonable groundwater drainage channel was reserved between pile groups, effectively reducing the groundwater level at the back of the pile group and reducing the landslide thrust behind the piles. After the completion of steel pipe pile construction, the overall stability of the landslide indicates that the treatment plan is reasonable and feasible, which can provide reference for the design and construction of similar landslide prevention projects.
2025, 39(1): 55-62.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0794
Abstract:
To study the influence of the shallow tunnel construction on the adjacent pile foundation and the reinforcement measures, this research relies on the Lu’ao Road underpassing Maqing Road project to establish a finite element model. The surface settlement caused by shallow tunnel excavation and the deformation and internal force distribution law of the pile foundation were analyzed. It was found that the maximum horizontal displacement of the pile foundation (3.63 mm) exceeded the deformation control index (3 mm) and had a large impact on the internal force of the adjacent pile foundation. The protective measures of grouting reinforcement were proposed, and the protective effects of different reinforcement depths were compared and analyzed. The results show that grouting reinforcement of the soil around the pile foundation can significantly reduce the deformation and internal force of the pile foundation, and better results can be achieved when the depth of grouting reinforcement is 15 m. The reliability of the model and the rationality of reinforcement measures are verified by comparing them with the field monitoring data.
To study the influence of the shallow tunnel construction on the adjacent pile foundation and the reinforcement measures, this research relies on the Lu’ao Road underpassing Maqing Road project to establish a finite element model. The surface settlement caused by shallow tunnel excavation and the deformation and internal force distribution law of the pile foundation were analyzed. It was found that the maximum horizontal displacement of the pile foundation (3.63 mm) exceeded the deformation control index (3 mm) and had a large impact on the internal force of the adjacent pile foundation. The protective measures of grouting reinforcement were proposed, and the protective effects of different reinforcement depths were compared and analyzed. The results show that grouting reinforcement of the soil around the pile foundation can significantly reduce the deformation and internal force of the pile foundation, and better results can be achieved when the depth of grouting reinforcement is 15 m. The reliability of the model and the rationality of reinforcement measures are verified by comparing them with the field monitoring data.
Reinforcement effect of middle partition wall in ultra-small spacing section of subway shield tunnel
2025, 39(1): 63-71.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0801
Abstract:
To explore the reinforcement effect of the middle partition wall in the ultra-small spacing section of the subway shield tunnel, based on the entrance and exit line project of the south parking lot of Guangzhou Metro Line 12, the FLAC 3D software was used to establish the simulation model of the shield tunnel construction, and to analyze the influence law of the ultra-small spacing shield tunnel construction on the surrounding rock and soil mass and the pre-built tunnel under the condition of unreinforced and middle partition wall reinforcement. The results show that with the increase of shield excavation depth, the surface settlement, the horizontal displacement of soil and the deformation of the tunnel segment were obviously increased, and the stability of the middle rock column was reduced. The reinforcement effect of the middle partition wall was remarkable. Compared with the unreinforced condition, when the project was excavated to the 19th ring, the maximum surface settlement and horizontal displacement of the soil were reduced by 31.1% and 70%, respectively. The maximum lateral expansion and vertical deformation of the first tunnel segment were reduced by 56.8% and 73.5%, respectively. The stability of the middle rock column was obviously improved. Therefore, the middle partition wall can play a good reinforcement effect in the ultra-small clear distance section.
To explore the reinforcement effect of the middle partition wall in the ultra-small spacing section of the subway shield tunnel, based on the entrance and exit line project of the south parking lot of Guangzhou Metro Line 12, the FLAC 3D software was used to establish the simulation model of the shield tunnel construction, and to analyze the influence law of the ultra-small spacing shield tunnel construction on the surrounding rock and soil mass and the pre-built tunnel under the condition of unreinforced and middle partition wall reinforcement. The results show that with the increase of shield excavation depth, the surface settlement, the horizontal displacement of soil and the deformation of the tunnel segment were obviously increased, and the stability of the middle rock column was reduced. The reinforcement effect of the middle partition wall was remarkable. Compared with the unreinforced condition, when the project was excavated to the 19th ring, the maximum surface settlement and horizontal displacement of the soil were reduced by 31.1% and 70%, respectively. The maximum lateral expansion and vertical deformation of the first tunnel segment were reduced by 56.8% and 73.5%, respectively. The stability of the middle rock column was obviously improved. Therefore, the middle partition wall can play a good reinforcement effect in the ultra-small clear distance section.
2025, 39(1): 72-81.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0806
Abstract:
In a foundation pit located in an expansive soil area in Chengdu, an h-type double-row pile + anchor cable support system was employed. FLAC 3D was used to conduct numerical simulations analyzing the effects of varying pile row spacing, and differences in pile top and bottom elevations. The analysis shows that when row spacings are less than five times the pile diameter (5d), increasing the spacing leeds to more reasonable force distribution on the piles. As the top of the front pile decreases, the bending moment and shear force shared by the rear pile increase, yet its maximum shear force remains lower than that of the front row. Elevating the rear row pile bottom resulted in a sharp decrease and misallocation of its bending moment and shear force. Based on these findings, the h-type double-row pile design was optimized by adding supporting blind ditches between tie beams and inclined drainage holes between piles, effectively mitigating expansive soil relaxation and preventing shear strength reduction due to moisture increases. Monitoring data confirmed effective deformation control and validated the reliability of the numerical model.
In a foundation pit located in an expansive soil area in Chengdu, an h-type double-row pile + anchor cable support system was employed. FLAC 3D was used to conduct numerical simulations analyzing the effects of varying pile row spacing, and differences in pile top and bottom elevations. The analysis shows that when row spacings are less than five times the pile diameter (5d), increasing the spacing leeds to more reasonable force distribution on the piles. As the top of the front pile decreases, the bending moment and shear force shared by the rear pile increase, yet its maximum shear force remains lower than that of the front row. Elevating the rear row pile bottom resulted in a sharp decrease and misallocation of its bending moment and shear force. Based on these findings, the h-type double-row pile design was optimized by adding supporting blind ditches between tie beams and inclined drainage holes between piles, effectively mitigating expansive soil relaxation and preventing shear strength reduction due to moisture increases. Monitoring data confirmed effective deformation control and validated the reliability of the numerical model.
2025, 39(1): 82-88.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0820
Abstract:
The Lishui Wentouling landslide, Foshan City was investigated through investigation, drilling, and monitoring methods. The geological environmental conditions and disaster characteristics of the landslide area were identified, and the influencing factors and sliding mechanism were analyzed. The results show that: (1) the overall trend is that the larger the rainfall, the faster the sliding, with a sliding rainfall value of about 30 mm; (2) The development of coal bearing strata, along slope and fold structures are inherent factors in the formation of landslides. The excavation and long-term infiltration of rainwater into the coarse sandstone belt, resulting in static water pressure, are indirect triggering factors for landslide formation. Heavy rainfall is the direct triggering factor for landslide formation; (3) The sliding mechanism mode is characterized by early infiltration of rainwater and accelerated formation of sliding surfaces along the interface of carbonaceous mudstone due to softening of runoff. In the middle stage, excavation at the foot of the slope, combined with the gravity of the rock and soil mass on the slope and the static water pressure at the foot of the slope, acts downwards to penetrate the sliding surface. In the later stage, heavy rainfall induces landslides. This research can provide reference for the investigation, evaluation, monitoring, early warning, and subsequent prevention and control of landslides in similar coal bearing strata.
The Lishui Wentouling landslide, Foshan City was investigated through investigation, drilling, and monitoring methods. The geological environmental conditions and disaster characteristics of the landslide area were identified, and the influencing factors and sliding mechanism were analyzed. The results show that: (1) the overall trend is that the larger the rainfall, the faster the sliding, with a sliding rainfall value of about 30 mm; (2) The development of coal bearing strata, along slope and fold structures are inherent factors in the formation of landslides. The excavation and long-term infiltration of rainwater into the coarse sandstone belt, resulting in static water pressure, are indirect triggering factors for landslide formation. Heavy rainfall is the direct triggering factor for landslide formation; (3) The sliding mechanism mode is characterized by early infiltration of rainwater and accelerated formation of sliding surfaces along the interface of carbonaceous mudstone due to softening of runoff. In the middle stage, excavation at the foot of the slope, combined with the gravity of the rock and soil mass on the slope and the static water pressure at the foot of the slope, acts downwards to penetrate the sliding surface. In the later stage, heavy rainfall induces landslides. This research can provide reference for the investigation, evaluation, monitoring, early warning, and subsequent prevention and control of landslides in similar coal bearing strata.
2025, 39(1): 89-96.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0822
Abstract:
The deformation of adjacent existing buildings induced by deep foundation pit excavation and unloading poses a significant and challenging issue in urban infrastructure construction. A numerical analysis model was established based on the reconstruction and expansion project of a building in Xi’an. Different supporting structures and the spacing between buildings and the foundation pit were investigated as research variables to analyze the impact characteristics of deep foundation pit excavation on adjacent existing buildings under various working conditions. The results revealed that the pile-anchor support system exhibited the best enclosure effect, while double-row piles could also achieve good supporting performance under appropriate pile spacing. Furthermore, the disturbance caused by foundation pit excavation has a limited range; specifically, buildings located beyond 12 m from the excavation site experienced negligible disturbance that did not compromise their safe use.
The deformation of adjacent existing buildings induced by deep foundation pit excavation and unloading poses a significant and challenging issue in urban infrastructure construction. A numerical analysis model was established based on the reconstruction and expansion project of a building in Xi’an. Different supporting structures and the spacing between buildings and the foundation pit were investigated as research variables to analyze the impact characteristics of deep foundation pit excavation on adjacent existing buildings under various working conditions. The results revealed that the pile-anchor support system exhibited the best enclosure effect, while double-row piles could also achieve good supporting performance under appropriate pile spacing. Furthermore, the disturbance caused by foundation pit excavation has a limited range; specifically, buildings located beyond 12 m from the excavation site experienced negligible disturbance that did not compromise their safe use.
2025, 39(1): 97-104.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0886
Abstract:
Taking a deep foundation pit in Wuhan as an example, the control effectiveness of the pre-stressed fish-bellied beam steel support system on the overall deformation was analyzed. The influence of the degree of pre-stress, the pile diameter of the enclosing piles and the spacing of the piles on the deformation of the fish-belly beam steel support system was studied. The study shows that: the lateral deformation of the steel support structure system of the fish-belly beam, the deep lateral displacement of the enclosure structure and the ground settlement outside the pit do not exceed the warning value of the pit, and the application of pre-stress can effectively control the maximum lateral displacement of the enclosure structure, and the control effect is better at the position of the fish-belly beam, and the overall safety of the construction of the pit is greatly improved. Increasing the degree of pre-stress, the diameter of the enclosing piles, and reducing the pile spacing can reduce the overall deformation of the foundation pit to a certain extent. Within a reasonable range, compared with the spacing of the enclosing piles, the change of pile diameter has a greater influence on the maximum lateral deformation of the fish-belly beam steel support system, the maximum lateral displacement of the deep layer of the enclosing structure, and the maximum settlement of the ground surface outside the pit, which has a more significant effect on the overall deformation of the foundation pit.
Taking a deep foundation pit in Wuhan as an example, the control effectiveness of the pre-stressed fish-bellied beam steel support system on the overall deformation was analyzed. The influence of the degree of pre-stress, the pile diameter of the enclosing piles and the spacing of the piles on the deformation of the fish-belly beam steel support system was studied. The study shows that: the lateral deformation of the steel support structure system of the fish-belly beam, the deep lateral displacement of the enclosure structure and the ground settlement outside the pit do not exceed the warning value of the pit, and the application of pre-stress can effectively control the maximum lateral displacement of the enclosure structure, and the control effect is better at the position of the fish-belly beam, and the overall safety of the construction of the pit is greatly improved. Increasing the degree of pre-stress, the diameter of the enclosing piles, and reducing the pile spacing can reduce the overall deformation of the foundation pit to a certain extent. Within a reasonable range, compared with the spacing of the enclosing piles, the change of pile diameter has a greater influence on the maximum lateral deformation of the fish-belly beam steel support system, the maximum lateral displacement of the deep layer of the enclosing structure, and the maximum settlement of the ground surface outside the pit, which has a more significant effect on the overall deformation of the foundation pit.
2025, 39(1): 105-112.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0887
Abstract:
To solve the construction issues of irregular connection passages in subway tunnels with significant gaps and vertical misalignments, a structural scheme involving the incorporation of vertical shafts at the midpoint of the connection passage was proposed, alongside a dual-channel method where both the upper and lower passages were separately frozen and constructed. An empirical study scrutinizing the patterns of temperature variations and ground surface displacements during the freezing process was conducted, revealing the following results: (1) The fluctuations in temperature recorded at the monitoring holes during the freezing phase can be delineated into three distinct stages: a rapid decline in temperature during the early active freezing stage, followed by a stable decrease in temperature in the latter part of the active freezing stage, temperature stability in the early stage of the segment and finally a sustained increase in temperature during the later part of the maintenance freezing stage, exacerbated by ongoing excavation activities; (2) The speed of inward expansion of the freezing wall was found to be approximately 1.1 times higher than the outward expansion rate, illustrating a predominant inward growth during the freezing operations; (3) The ground deformation within the connection passage exhibited a rapid uplift during the active freezing phase. This was counterbalanced during the maintenance freezing phase, where the uplift induced by freezing was largely offset by the settlement caused by excavation, thus resulting in a generally stable trend; (4) At various burial depths, both vertical and horizontal ground freezing expansion uplift rates demonstrated a gradual decrease from the central axis of the connection passage moving towards either side. Furthermore, it was observed that greater burial depths resulted in a reduced discrepancy in ground freezing uplift rates; (5) The structural approach of installing vertical shafts at the midpoint of the irregular connection passage, complemented by individual freezing plans for the two vertically misaligned passages in the wide-spacing subway tunnel, proved to be a rational and viable solution for similar engineering projects.
To solve the construction issues of irregular connection passages in subway tunnels with significant gaps and vertical misalignments, a structural scheme involving the incorporation of vertical shafts at the midpoint of the connection passage was proposed, alongside a dual-channel method where both the upper and lower passages were separately frozen and constructed. An empirical study scrutinizing the patterns of temperature variations and ground surface displacements during the freezing process was conducted, revealing the following results: (1) The fluctuations in temperature recorded at the monitoring holes during the freezing phase can be delineated into three distinct stages: a rapid decline in temperature during the early active freezing stage, followed by a stable decrease in temperature in the latter part of the active freezing stage, temperature stability in the early stage of the segment and finally a sustained increase in temperature during the later part of the maintenance freezing stage, exacerbated by ongoing excavation activities; (2) The speed of inward expansion of the freezing wall was found to be approximately 1.1 times higher than the outward expansion rate, illustrating a predominant inward growth during the freezing operations; (3) The ground deformation within the connection passage exhibited a rapid uplift during the active freezing phase. This was counterbalanced during the maintenance freezing phase, where the uplift induced by freezing was largely offset by the settlement caused by excavation, thus resulting in a generally stable trend; (4) At various burial depths, both vertical and horizontal ground freezing expansion uplift rates demonstrated a gradual decrease from the central axis of the connection passage moving towards either side. Furthermore, it was observed that greater burial depths resulted in a reduced discrepancy in ground freezing uplift rates; (5) The structural approach of installing vertical shafts at the midpoint of the irregular connection passage, complemented by individual freezing plans for the two vertically misaligned passages in the wide-spacing subway tunnel, proved to be a rational and viable solution for similar engineering projects.
2025, 39(1): 113-121.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0918
Abstract:
In the construction of shield tunnels within ultra-small clear distance stacked line sections, the control of the deformation and stress state of the tunnel lining segments is critical for ensuring construction safety. During the construction of Guangzhou Metro Line 12, the leading tunnel was reinforced using a support trolley. To examine the efficacy of this reinforcement, a computational model was developed utilizing the finite difference software FLAC 3D. Comparative analysis was conducted on the deformation and stress state settlement of tunnel segments under two conditions: without reinforcement measures and with the use of supporting trolleys. The findings indicated that the influence of tunnel segment deformation extended approximately 5 m from the excavation face. The application of the support trolley significantly reduced the maximum vertical and lateral deformations of the segments by 42.7% and 56.7%, respectively. Additionally, the vertical deformation of adjacent existing tunnels was reduced by 14.4% to 24.71%, thereby enhancing operational safety. Furthermore, the use of the support trolley did not induce cracking in the segments but resulted in localized stress concentrations.
In the construction of shield tunnels within ultra-small clear distance stacked line sections, the control of the deformation and stress state of the tunnel lining segments is critical for ensuring construction safety. During the construction of Guangzhou Metro Line 12, the leading tunnel was reinforced using a support trolley. To examine the efficacy of this reinforcement, a computational model was developed utilizing the finite difference software FLAC 3D. Comparative analysis was conducted on the deformation and stress state settlement of tunnel segments under two conditions: without reinforcement measures and with the use of supporting trolleys. The findings indicated that the influence of tunnel segment deformation extended approximately 5 m from the excavation face. The application of the support trolley significantly reduced the maximum vertical and lateral deformations of the segments by 42.7% and 56.7%, respectively. Additionally, the vertical deformation of adjacent existing tunnels was reduced by 14.4% to 24.71%, thereby enhancing operational safety. Furthermore, the use of the support trolley did not induce cracking in the segments but resulted in localized stress concentrations.
2025, 39(1): 122-131.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0874
Abstract:
To enhance the seismic resilience of structures, isolation and damping technologies along with high-performance materials have been widely adopted in the construction of buildings and bridges. However, optimizing seismic performance in geotechnical retaining structures remains relatively underdeveloped. Therefore, this study introduced an energy-dissipating pile-anchor structure developed using Engineered Cementitious Composite (ECC) materials and viscous damping technology, and its seismic performance was assessed through shaking table tests. The dynamic response characteristics of the new structure were analyzed, focusing on acceleration response, Hilbert spectral changes, and dynamic shear stress-strain behaviors. The analysis indicates that the energy-dissipating pile-anchor system increases the energy absorption of superficial soil layers during seismic events, effectively reducing the energy transmitted to the pile body and thus mitigating damage to the support structure. Additionally, the research found that the Hilbert spectrum accurately describes the time-frequency characteristics of seismic waves, providing a comprehensive view of the structural dynamics. These results offer references for the optimization of seismic resilience in anchor-supported slide-resistant pile structures.
To enhance the seismic resilience of structures, isolation and damping technologies along with high-performance materials have been widely adopted in the construction of buildings and bridges. However, optimizing seismic performance in geotechnical retaining structures remains relatively underdeveloped. Therefore, this study introduced an energy-dissipating pile-anchor structure developed using Engineered Cementitious Composite (ECC) materials and viscous damping technology, and its seismic performance was assessed through shaking table tests. The dynamic response characteristics of the new structure were analyzed, focusing on acceleration response, Hilbert spectral changes, and dynamic shear stress-strain behaviors. The analysis indicates that the energy-dissipating pile-anchor system increases the energy absorption of superficial soil layers during seismic events, effectively reducing the energy transmitted to the pile body and thus mitigating damage to the support structure. Additionally, the research found that the Hilbert spectrum accurately describes the time-frequency characteristics of seismic waves, providing a comprehensive view of the structural dynamics. These results offer references for the optimization of seismic resilience in anchor-supported slide-resistant pile structures.
2025, 39(1): 132-138.
doi: 10.20265/j.cnki.issn.1007-2993.2023-0534
Abstract:
To ensure subgrade compaction quality, the correlation between compaction state and rolling dynamic soil pressure was investigated. An indoor calibration test of soil pressure sensors was conducted, revealing a difference of over 65% between the sand calibration coefficient and the manufacturer's coefficient. This emphasized the necessity of selecting the medium based on actual engineering conditions for calibration. The relationship between the calibration coefficient and compaction state was clarified, leading to the establishment of a calibration coefficient - sand compaction degree curve and a normalization equation. Field measurements show that correcting measured values using actual medium calibration coefficients reduces the deviation from the Boussinesq theoretical solution by an average of 29.4%, compared to using the manufacturer’s coefficients.
To ensure subgrade compaction quality, the correlation between compaction state and rolling dynamic soil pressure was investigated. An indoor calibration test of soil pressure sensors was conducted, revealing a difference of over 65% between the sand calibration coefficient and the manufacturer's coefficient. This emphasized the necessity of selecting the medium based on actual engineering conditions for calibration. The relationship between the calibration coefficient and compaction state was clarified, leading to the establishment of a calibration coefficient - sand compaction degree curve and a normalization equation. Field measurements show that correcting measured values using actual medium calibration coefficients reduces the deviation from the Boussinesq theoretical solution by an average of 29.4%, compared to using the manufacturer’s coefficients.
Jet grouting materials in sandy silt soil layer considering the time-dependent behavior of viscosity
2025, 39(1): 139-149.
doi: 10.20265/j.cnki.issn.1007-2993.2024-0007
Abstract:
Jet grouting technology is widely used in hydraulic engineering, foundation engineering, underground engineering, and deep excavation engineering. However, in fine sandy silt soil strata, conventional cement-based solidifiers result in poor construction quality due to the slurry's tendency to disperse under high pressure. To address this, an efficient rapid-setting material was developed, enabling faster slurry solidification and improved performance in fine sand soils. Based on a theoretical model of jet grouting erosion, a method for calculating slurry diffusion distance that considers viscosity changes over time was proposed. Viscosity tests were conducted on cement-water glass slurries at various ratios, analyzing how viscosity evolved with time. Considering gelation time, material strength, and slurry diffusion distance, the study optimized the mix ratio of cement-water glass rapid-setting materials for fine sand soil layers. The recommended mix ratio was determined to be a water-cement ratio of 1.0 to 1.2 and a volume ratio of 1∶0.1. This research provides references for optimizing rapid-setting slurries for jet grouting applications, offering practical guidance for enhancing construction practices in challenging soil conditions.
Jet grouting technology is widely used in hydraulic engineering, foundation engineering, underground engineering, and deep excavation engineering. However, in fine sandy silt soil strata, conventional cement-based solidifiers result in poor construction quality due to the slurry's tendency to disperse under high pressure. To address this, an efficient rapid-setting material was developed, enabling faster slurry solidification and improved performance in fine sand soils. Based on a theoretical model of jet grouting erosion, a method for calculating slurry diffusion distance that considers viscosity changes over time was proposed. Viscosity tests were conducted on cement-water glass slurries at various ratios, analyzing how viscosity evolved with time. Considering gelation time, material strength, and slurry diffusion distance, the study optimized the mix ratio of cement-water glass rapid-setting materials for fine sand soil layers. The recommended mix ratio was determined to be a water-cement ratio of 1.0 to 1.2 and a volume ratio of 1∶0.1. This research provides references for optimizing rapid-setting slurries for jet grouting applications, offering practical guidance for enhancing construction practices in challenging soil conditions.
2025, 39(1): 150-158.
doi: 10.20265/j.cnki.issn.1007-2993.2024-0012
Abstract:
During pipe jacking construction, a large amount of silt will be generated, which has characteristics such as high moisture content, poor stability, and uneven particle distribution. Mud solidification technology is an important means for the reuse of construction waste. To improve the strength of mud consolidation and explore the efficient formula of stabilizing agents, sand strength tests, unconfined compressive strength tests, X-ray diffraction analysis, specific surface and pore size analysis tests, FTIR Fourier transform infrared spectroscopy analysis were used to detect the strength of stabilizing agents and consolidation bodies. The changes in the composition of consolidation bodies, internal porosity changes, and molecular bonds in the microstructure were studied. The results show that using construction waste, phosphogypsum, and slag as raw materials, a ratio (top pipe sludge: construction waste: phosphogypsum: slag=0.40:0.55:0.015:0.052) was selected to meet the strength requirements of domestic solid waste base materials for road subgrade. After 28 days of curing, the moisture content of the samples was 1.32%～2.89%, and the compressive strength was 3.3～6.6 MPa.
During pipe jacking construction, a large amount of silt will be generated, which has characteristics such as high moisture content, poor stability, and uneven particle distribution. Mud solidification technology is an important means for the reuse of construction waste. To improve the strength of mud consolidation and explore the efficient formula of stabilizing agents, sand strength tests, unconfined compressive strength tests, X-ray diffraction analysis, specific surface and pore size analysis tests, FTIR Fourier transform infrared spectroscopy analysis were used to detect the strength of stabilizing agents and consolidation bodies. The changes in the composition of consolidation bodies, internal porosity changes, and molecular bonds in the microstructure were studied. The results show that using construction waste, phosphogypsum, and slag as raw materials, a ratio (top pipe sludge: construction waste: phosphogypsum: slag=0.40:0.55:0.015:0.052) was selected to meet the strength requirements of domestic solid waste base materials for road subgrade. After 28 days of curing, the moisture content of the samples was 1.32%～2.89%, and the compressive strength was 3.3～6.6 MPa.
2017, 31(3): 153-159,163.
doi: 10.3969/j.issn.1007-2993.2017.03.010
摘要：
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
2020, 34(3): 143-149.
doi: 10.3969/j.issn.1007-2993.2020.03.005
摘要：
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
2016, 30(2): 85-88.
doi: 10.3969/j.issn.1007-2993.2016.02.007
摘要：
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
2016, 30(1): 6-11.
doi: 10.3969/j.issn.1007-2993.2016.01.002
摘要：
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
2016, 30(1): 12-19,38.
doi: 10.3969/j.issn.1007-2993.2016.01.003
摘要：
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
3D Laser Scanning Technology and BIM Technology in Ancient Building Protection Surveying and Mapping
2019, 33(4): 222-225.
doi: 10.3969/j.issn.1007-2993.2019.04.008
摘要：
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
2018, 32(4): 189-193,198.
doi: 10.3969/j.issn.1007-2993.2018.04.006
摘要：
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
2019, 33(2): 84-88.
doi: 10.3969/j.issn.1007-2993.2019.02.006
摘要：
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
2019, 33(2): 115-120.
doi: 10.3969/j.issn.1007-2993.2019.02.013
摘要：
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
2017, 31(1): 49-54.
doi: 10.3969/j.issn.1007-2993.2017.01.012
摘要：
为了研究邕江北岸Ⅱ级阶地地区浅埋大断面(6.9 m×4.9 m)矩形顶管在复杂环境下长距离掘进过程中的地表沉降规律及控制措施,依托南宁地铁1号线金湖广场站Ⅲ号出入口工程,采用三维有限差分软件FLAC3D模拟顶管施工过程,并与实际监测结果作对比验证,结果表明:①在顶进过程中顶管机前方土体的主要扰动范围为两倍洞宽;②地表横向沉降曲线以顶管轴线为中心呈正态分布,地表沉降的横向影响范围为三倍洞宽;③通过顶管机头上抬、加设注浆套板、管节减摩注浆以及合理的顶进参数,确保地表隆起和沉降量均在合理控制的范围内。
为了研究邕江北岸Ⅱ级阶地地区浅埋大断面(6.9 m×4.9 m)矩形顶管在复杂环境下长距离掘进过程中的地表沉降规律及控制措施,依托南宁地铁1号线金湖广场站Ⅲ号出入口工程,采用三维有限差分软件FLAC3D模拟顶管施工过程,并与实际监测结果作对比验证,结果表明:①在顶进过程中顶管机前方土体的主要扰动范围为两倍洞宽;②地表横向沉降曲线以顶管轴线为中心呈正态分布,地表沉降的横向影响范围为三倍洞宽;③通过顶管机头上抬、加设注浆套板、管节减摩注浆以及合理的顶进参数,确保地表隆起和沉降量均在合理控制的范围内。
2021, 35(4): 269-274.
doi: 10.3969/j.issn.1007-2993.2021.04.012
Abstract:
2021, 35(1): 1-6,11.
doi: 10.3969/j.issn.1007-2993.2021.01.001
Abstract:
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Science & Technology Information Network of Geotechnical Engineering of National Defence & Machinery Industry; China Ordance Industry Survey and Geotechnical Institute Co., Ltd.
ISSN：1007-2993
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